216 ORGANIC EVOLUTION CONSIDERED 



compared with the temperature of its reptilian ances- 

 tors, would have rendered incubation necessary. 



What assurance was there, however, that a change 

 from a cold-blooded to a warm-blooded animal would 

 be accompanied by the evolution of an instinct so 

 persistent and necessary? The same question arises 

 in case of the great number of instincts of animals 

 which are accompanied by peculiarities of structure 

 which render the instincts useful. I do not think it 

 possible that they could all have originated by chance 

 — the instinct and the structure being perfectly 

 adapted to each other, yet neither being the cause of 

 the other. 



A colony of bees, with their peculiarities of struc- 

 ture, and their numerous instincts adapted to their 

 organization, is like a complex machine, from which, 

 if a single wheel were omitted, the whole would be 

 rendered useless. It is just as inconceivable, to my 

 mind, that a colony of bees could be evolved, with all 

 of their highly-developed and perfectly adapted in- 

 stincts and structures, as that a watch could be thus 

 produced. 



The hen during the time of incubation turns her 

 eggs over every day. This is said to be necessary in 

 order to keep the yolk of the egg in the proper posi- 

 tion. The instinct to turn the egg is necessary on 

 account of the structure of the egg itself. But it is 

 evident that the instinct and the structure of the 

 egg do not bear to each other the relation of cause 

 and effect. To claim that this and the vast number of 

 other similar instances are due to correlation of 

 growth is to make a claim without a shadow of proof. 



The yolk of the egg is held in position by tougher 

 portions of albumen extending from the ends of the 

 egg to the yolk. The latter turns on its axis, so that 

 the germ-yolk is kept on top near the warm body of 



